1. Field of the Invention
This invention relates to reclining chairs and more particularly, to mechanisms for reclining the seat and back portion of such reclining chairs.
2. Prior Art
In the prior art, there are several different types of reclining chairs. All of these reclining chairs essentially perform the same function. That is the function of reclining; however, these prior art reclining chairs all have certain deficiencies. In particular, when the chairs recline, the feet of the person sitting in the chair rise off the floor as the front portion of the seat rises. Such a condition is particularly undesirable in reclining chairs utilized in offices.
The reclining mechanism is usually further provided with a spring which can be adjusted for preload for varying the biasing force against the reclining motion of the chair so that the chair cannot fall backward with the person in it; however, this spring can be adjusted only for preload and nothing else. Preload adjustability alone does not provide the capability for equal starting positions for large and small persons and does not provide the same feel throughout the range of reclining travel for large and small persons. As a result, chairs with only preload adjustability are optimized essentially for only one size person. Therefore, chairs which are designed for people who are heavy cannot be utilized by people who are light in weight and vice versa.
There does exist reclining chairs in the prior art which reduce or eliminate the first above disadvantage; however, while these prior art reclining chairs may reduce or eliminate this disadvantage, they have other disadvantages of their own. Examples of such disadvantages are that they are complex in structure, difficult and expensive to manufacture and do not feel equally comfortable during reclining motion for both light and heavy weight persons.
Examples of prior art reclining chairs which possess one or more of the above disadvantages and which may have attempted to solve some of the above-described disadvantages are described in the issued patents as follows:
United States:
German:
DE4220881-A1
The inventors have invented a mechanism for reclining chairs which overcomes most of the disadvantages of the prior art. This invention is embodied in the U.S. Pat. No. 5,918,935. However, the inventors have now made improvements on their previous invention in order to provide an even superior mechanism.
Accordingly, it is a general object of the present invention to solve the disadvantages described above in the prior art and provide an improved mechanism.
In particular, it is a specific object of the present invention to provide a reclining chair which does not raise the feet of a person who is seated in the chair as it reclines, does not cause discomfort to the person seated in the chair as it reclines, is capable of being utilized equally comfortably by both heavy and lightweight persons, is easier to manufacture, reclines smoother and is easier to adjust.
It is yet another object of the present invention to provide a reclining chair with simultaneous adjustment of both the preload and the spring rate.
It is another object of the present invention to provide a reclining chair which will provide equal performance for a wide size range of persons.
It is still another object of the present invention to provide a reclining chair which includes a mechanism which is relatively simple in structure, easy to manufacture and low in cost to make.
In keeping with the principles and objects of the present invention, the objects are accomplished by a unique reclining chair including a support base, a chair comprising at least a seat portion, a means for coupling a forward portion of the seat portion to the support base such that the seat portion moves substantially about a pivoting axis located adjacent to the forward portion, a substantially vertically disposed coil spring means provided adjacent to the forward portion of the seat portion and between the seat portion and the support base, a means for coupling ends of the coil spring means pivotally to the seat portion and the support base and a means for pivoting one end of the coil spring means about an other end of the coil spring means whereby a force per unit distance of reclining of the seat portion as the chair is reclined may be varied and a reclining chair which is comfortable to sit in by both heavy and lightweight persons is provided.
Still further, in order to provide a means for more easily and quickly adjusting the means for pivoting one end of the coil spring means about the other end of the coil spring means, an offset crank shaft is provided as an improvement over the knob so as to provide more leverage and torque and a more ergonomically desirable motion for quick and easy adjustment of the means for pivoting one end of the coil spring to thereby vary the force per unit distance of reclining of the seat portion. Also, in another embodiment a boomerang shaped bell crank is used which simplifies the mechanism and reduces the load on the offset crankshaft.